US20050200647A1 - Droplet ejecting apparatus - Google Patents
Droplet ejecting apparatus Download PDFInfo
- Publication number
- US20050200647A1 US20050200647A1 US11/075,055 US7505505A US2005200647A1 US 20050200647 A1 US20050200647 A1 US 20050200647A1 US 7505505 A US7505505 A US 7505505A US 2005200647 A1 US2005200647 A1 US 2005200647A1
- Authority
- US
- United States
- Prior art keywords
- nozzle
- droplet
- ejection
- trajectory
- ink
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/21—Ink jet for multi-colour printing
- B41J2/2107—Ink jet for multi-colour printing characterised by the ink properties
- B41J2/211—Mixing of inks, solvent or air prior to paper contact
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/135—Nozzles
- B41J2/14—Structure thereof only for on-demand ink jet heads
- B41J2002/14475—Structure thereof only for on-demand ink jet heads characterised by nozzle shapes or number of orifices per chamber
Definitions
- the present invention relates to an apparatus for ejecting droplets such as an ink-jet printer capable of ejecting very small droplets.
- each ink droplet to be ejected from a printing head is as small as possible in order to improve print quality.
- an existing ink-jet printing head is capable of ejecting small ink droplets of about 2 pico-liter (pl) by, for example, modifying a control pulse waveform for an actuator to apply ejection energy to ink, or decreasing the diameter of each nozzle.
- a technique to regulate a control pulse waveform and, at the same time, to regulate a distance between the nozzle and a print medium such that a main dot (a main ink droplet) and a satellite dot (a satellite ink droplet), both of which are ejected through a nozzle in accordance with one pressure variation, may have substantially the same volume and such that landing positions of those two ink droplets may be different from each other (see Japanese Patent Application Laid-open No. 7-285222 ( FIG. 1 )).
- the size of the main ink droplet can be decreased, besides the satellite ink droplet can be increased in size and thus this can be a dot independent of the main dot.
- U.S. Patent Application Publication No. U.S. 2004/0046825 A1 discloses an apparatus for ejecting very small droplets to form dots on a print medium, the apparatus characterized by including: a first droplet ejector capable of ejecting a first main droplet in a first trajectory and a satellite droplet smaller in volume than the first main droplet, the satellite droplet being ejected together with the first main droplet; a second droplet ejector capable of ejecting a droplet having a second trajectory intersecting the first trajectory; and a control unit for controlling the first and second droplet ejectors so that the first main droplet and the droplet ejected from the second droplet ejector collide to unite with each other and a united droplet flies in a trajectory different from the first trajectory and the satellite droplet lands on the print medium.
- actuators are separately provided to drive the first and second droplet ejectors.
- U.S. Pat. No. 6,167,748 (corresponding to Japanese Patent Application Laid-open No. 11-99651) discloses a liquid discharge method and apparatus which enables, for example, a gradation recording by ejecting two droplets respectively from first and second discharge ports and by colliding these droplets to unite with each other while these droplets are flying.
- the first and second discharge openings are provided with first and second flow paths which communicate therewith respectively, and first and second energy generating devices for discharging the droplets therefrom respectively.
- Japanese Patent Application Laid-open No. 2001-239681 discloses that a plurality of droplets discharged from a plurality of nozzles are made to unite with each other to land on a recording paper. Each of the plurality of nozzles communicates with a flow path provided with a heater.
- a main object of the present invention is to provide an apparatus for ejecting droplets capable of ejecting very small droplets.
- an apparatus for ejecting droplets to form dots on a medium comprising: an ejection pressure applying section which applies ejection pressure to a storage chamber which stores liquid; a first nozzle which communicates with the storage chamber and which ejects a first main droplet in a first trajectory together with a satellite droplet having a volume smaller than the first main droplet; a second nozzle which communicates with the storage chamber and which ejects a second main droplet in a second trajectory intersecting the first trajectory at a predetermined intersection point; a control device which controls the ejection pressure applying section; and a medium holding device which holds the medium; wherein the control device controls the ejection pressure applying section so that the first main droplet and the second main droplet collide with each other at the intersection point to form a united droplet, and the satellite droplet, which has been ejected from the first nozzle, lands on the medium.
- an apparatus for ejecting droplets to form dots on a medium comprising: an ejection pressure applying section which applies ejection pressure to a storage chamber which stores liquid; a first nozzle which communicates with the storage chamber and which ejects a first main droplet in a first trajectory; a second nozzle which communicates with the storage chamber and which ejects a second main droplet in a second trajectory intersecting the first trajectory at a predetermined intersection point; a control device which controls the ejection pressure applying section so as to eject from the first nozzle the first main droplet and a satellite droplet which has a volume smaller than the first main droplet and which flies apart from the first main droplet, and to eject from the second nozzle the second main droplet which collides with the first main droplet at the intersection point to form a united droplet; and a print medium holding device which holds the medium at a position intersecting a trajectory of the satellite droplet.
- the satellite droplet (very small droplet), ejected together with the first main droplet and having a volume smaller than the first main droplet, land on the medium in order to form a very small dot.
- a droplet ejecting apparatus which allows the very small droplet to land on the medium with only one ejection pressure applying section. Accordingly, such an apparatus can be realized at a low cost.
- a flying direction of the united droplet may be different from a flying direction of the satellite droplet ejected from the first nozzle. Accordingly, it is possible to form a dot on the medium only with the satellite droplet, without making the united droplet land on the medium.
- a volume of the satellite droplet may be 0.002 to 0.5 pl. By adjusting the volume of the satellite droplet to this volume, it is possible to form an even smaller dot on the medium.
- the first trajectory may be perpendicular to a surface of the medium held in the medium holding device. Accordingly, it is possible to form a circular dot on the medium, thereby improving the image quality.
- an ejection port of the first nozzle and an ejection port of the second nozzle may be formed in a same plane. Accordingly, it is possible to easily form the first nozzle and the second nozzle, thereby decreasing the cost for manufacturing the droplet ejecting apparatus.
- a first plane in which an ejection port of the first nozzle is formed and a second plane in which the second nozzle is formed may be planes intersecting with each other; and the first nozzle may be formed so that an axis line of the first nozzle extends along the first trajectory, and the second nozzle may be formed so that an axis line of the second nozzle extends along the second trajectory. Accordingly, it is possible to form the first nozzle and the second nozzle so that the ejection characteristics are stabilized and the satellite droplet, the first and second main droplets are ejected with high precision.
- a nozzle diameter of the first nozzle at an ejection port thereof and a nozzle diameter of the second nozzle at an ejection port thereof may be different. Accordingly, it is possible to prevent the second nozzle from ejecting excess satellite droplets, thereby preventing the inconvenience that the medium is stained with the excess satellite droplets.
- a nozzle diameter of the first nozzle at an ejection port thereof may be smaller than a nozzle diameter of the second nozzle at an ejection port thereof; and a linear distance between the ejection port of the first nozzle and the intersection point may be longer than a linear distance between the ejection port of the second nozzle and the intersection point. Accordingly, it is possible to eject the satellite droplet from the first nozzle, to prevent the second nozzle from ejecting any satellite droplet, and to make the first main droplet and the second main droplet collide with each other.
- an ejection speed of the first main droplet ejected from the first nozzle may be not less than 4.5 m/sec and less than 7.0 m/sec; and an ejection speed of the second main droplet ejected from the second nozzle may be less than 4.5 m/sec. Accordingly, it is possible for the first nozzle to eject a desired satellite droplet, and for the second nozzle not to eject any satellite droplet.
- an ejection port of the first nozzle may have a circular or elliptic shape; and a trajectory of the satellite droplet may be same as the first trajectory. Accordingly, it is possible to eject the satellite droplet with high precision.
- an ejection port of the first nozzle may have a circular or elliptic shape in which a notch is formed in a portion of outer edge thereof; and a trajectory of the satellite droplet may be tilted toward the notch from the first trajectory. Accordingly, the satellite droplet and the second main droplet hardly collide with each other, because the satellite droplet will not pass through the intersection point.
- a droplet catching section for catching the united droplet may be disposed in a trajectory of the united droplet. Accordingly, the united droplet will never land on the medium and thus no excessive dots will be formed.
- the apparatus may further comprise a discharge passage for discharging the united droplet which has been caught in the droplet catching section. Accordingly, it is possible to discharge the liquid held by the droplet catching section, thereby decreasing the volume of the droplet catching section.
- the apparatus may further comprise a liquid chamber for supplying the liquid to the storage chamber; and a delivery passage for delivering the united droplet which has been caught in the droplet catching section to the liquid chamber. Accordingly, it is possible to recycle the united droplet and thus reduce the running cost.
- the delivery passage may suck up the united droplet to the liquid chamber by capillary force. Accordingly, it is possible to suck up the united droplet with a simple constitution with high efficiency.
- a droplet-ejecting head which forms dots on a medium
- the droplet-ejecting head comprising: an ejection surface in which a first nozzle and a second nozzle are formed, the second nozzle having an ejection direction different from an ejection direction of the first nozzle; a pressure chamber which is common to the first nozzle and the second nozzle, and which stores liquid to be ejected from the first nozzle and the second nozzle; and an actuator which applies ejection pressure to the pressure chamber. Since this droplet-ejecting head includes a pressure chamber and an actuator common to the first nozzle and the second nozzle, it is possible to practice the printing method as disclosed in U.S. Patent Application Publication No.
- the first and second nozzles may be formed to be tilted from a direction perpendicular to a surface of a nozzle plate.
- a nozzle diameter of the first nozzle may be different from a nozzle diameter of the second nozzle.
- FIG. 1 shows a perspective view illustrating a schematic arrangement of an ink-jet printer including an ink ejecting section according to a first embodiment of the present application.
- FIG. 2 shows a sectional view illustrating the ink ejecting section shown in FIG. 1 .
- FIG. 3 shows a sectional view illustrating the ink ejecting section taken along a line III-III shown in FIG. 2 .
- FIGS. 4A and 4B show a magnified view of nozzles shown in FIG. 3 .
- FIG. 5 shows a sectional view of an actuator in the ink ejecting section shown in FIG. 1 , when the actuator is driven.
- FIGS. 6A to 6 C are diagrams respectively illustrating states of ink droplets ejected from the nozzle shown in FIG. 3 .
- FIG. 7A shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown in FIG. 1 in chronological order.
- FIG. 7B shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown in FIG. 1 in chronological order.
- FIG. 7C shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown in FIG. 1 in chronological order.
- FIG. 7D shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown in FIG. 1 in chronological order.
- FIGS. 8A and 8B show sectional views illustrating a modification of the nozzles shown in FIG. 2 .
- FIGS. 9A and 9B show magnified views of nozzles of an ink ejecting section according to a second embodiment of the present application.
- FIGS. 10A to 10 D show sectional views illustrating an operation in which ink droplets are ejected from the nozzle shown in FIG. 9 .
- FIG. 11A shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown in FIG. 9 in chronological order.
- FIG. 11B shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown in FIG. 9 in chronological order.
- FIG. 11C shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown in FIG. 9 in chronological order.
- FIG. 11D shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown in FIG. 9 in chronological order.
- FIG. 1 shows a perspective view illustrating a schematic arrangement of an ink-jet printer including an ink ejecting section according to the first embodiment.
- FIG. 1 shows the ink-jet printer in a state in which a part of the printer is cut open. As shown in FIG.
- an ink-jet printer 1 includes therein platen rollers 40 a , 40 b as a transport means which transports a paper 41 as a medium and as a medium holding means (device) which holds the paper 41 at a recording position; guide rollers 42 a , 42 b which hold the paper 41 therebetween together with the platen rollers 40 a , 40 b ; an ink-jet head 10 which ejects ink droplets onto the paper 41 transported by the transport means; and a control device 20 .
- the platen rollers 40 a , 40 b are attached to a non-illustrated frame so as to be rotatable.
- the platen rollers 40 a , 40 b are driven by an electric motor 44 to rotate.
- the paper 41 is fed from a non-illustrated paper feed cassette provided in one side portion of the ink-jet printer 1 .
- the paper 41 is then transported by the platen rollers 40 a , 40 b at a constant speed. After printing is performed on the paper 41 with ink ejected from the ink-jet head 10 , the paper 41 is discharged from the ink-jet printer 1 .
- the ink-jet printer 1 of FIG. 1 is a monochrome printer and thus includes only one ink-jet head 10 . In the case a color printing is performed with the ink-jet printer 1 , at least four ink-jet heads 10 for yellow, magenta, cyan, and black are provided in parallel.
- the ink-jet head 10 is a line head extending perpendicularly to the transport direction of the paper 41 .
- the ink-jet head 10 is fixed to the frame so as to oppose to the paper 41 at a predetermined angle.
- a large number of nozzles 8 a , 8 b which eject ink droplets on the basis of control of the control device 20 , are arranged in a row in an ink-ejection surface (lower surface) of the ink-jet head 10 along the longitudinal direction of the ink-jet head 10 .
- the nozzles 8 a and 8 b are arranged side-by-side in a row so as to be along the widthwise direction of the ink-jet head 10 .
- the nozzle 8 a is formed so that the trajectory (first trajectory) of an ink droplet ejected from the nozzle 8 a is substantially perpendicular to the paper 41
- the nozzle 8 b is formed so that the trajectory (second trajectory) of an ink droplet ejected from the nozzle 8 b intersect the trajectory of the ink droplet ejected from the nozzle 8 a at a predetermined angle.
- a large number of actuators 21 which is controlled by the control device 20 for making nozzles 8 a , 8 b eject ink droplets, are arranged in a row on a surface (upper surface) opposite to the ink-ejecting surface of the ink-jet head 10 along the longitudinal direction of the ink-jet head 10 .
- each of the ink ejecting sections 100 includes a pair of nozzles 8 a , 8 b , one individual ink flow path 120 which communicates with the nozzles 8 a , 8 b , and one actuator 21 .
- a projection 10 a is arranged in the ink-ejecting surface of the ink-jet head 10 .
- the projection 10 a extends along the extending direction of ink-jet head 10 , and is an L-shaped in cross section in the widthwise direction thereof.
- the control device 20 controls the operations of parts or components of the ink-jet printer 1 , such as the electric motor 44 and the ink-jet head 10 . Particularly in this embodiment, the control device 20 perform control, in accordance with one ink ejection signal (which means a drive pulse corresponding to one dot on the paper 41 ), so that the nozzle 8 a ejects a main droplet (first main droplet) 61 having a relatively large diameter (for example, a diameter of about 4 to 25 ⁇ m) and a satellite droplet 63 which is smaller in volume than the main droplet 61 (for example, having a diameter of about 1.6 to 10 ⁇ m) after the ejection of the main droplet 61 , and at the same time, the nozzle 8 b ejects only one main droplet (second main droplet) 62 .
- one ink ejection signal which means a drive pulse corresponding to one dot on the paper 41
- the nozzle 8 a ejects a main droplet (first
- the ejection speed and the volume of the ink droplets can be controlled by adjusting at least one of the pulse height, the number of pulses, the pulse width of the ink ejection signal or the like on the basis of the dimension of the ejection port of nozzles 8 a , 8 b.
- FIG. 2 shows a sectional view illustrating the ink ejecting section 100 in the ink-jet head 10 .
- FIG. 3 shows a sectional view illustrating the ink ejecting section 100 taken along a line III-III shown in FIG. 2 .
- an actuator 21 which is driven with a drive pulse signal (which can take selectively one of the ground potential and a predetermined positive potential) generated in a non-illustrated drive circuit, and a flow path unit 4 forming an individual ink flow path are stacked in layers.
- a drive pulse signal which can take selectively one of the ground potential and a predetermined positive potential
- the actuator 21 and flow path unit 4 are bonded to each other with an epoxy-base thermo-curable adhesive.
- a flexible printer wiring board (not illustrated) is bonded to the upper surface of the actuator 21 .
- the ink-ejection surface of the flow path unit 4 is fitted with an edge of the projection 10 a in a perpendicular direction.
- the flow path unit 4 is constructed by stacking in layers: four thin-shaped plates formed of a metal material (an actuator plate 22 , a cavity plate 23 , a supply plate 24 , and a manifold plate 25 ); and a nozzle plate 26 which is formed of a synthetic resin such as polyimide and which includes nozzles 8 a , 8 b for ejecting an ink.
- the actuator plate 22 in the uppermost layer is in contact with the actuator 21 .
- a plurality of pressure chambers 110 are formed for storing ink to be selectively ejected by an action of the actuator 21 .
- the pressure chambers 110 are arranged in a row along the longitudinal direction of the ink-jet head 10 (a direction perpendicular to the sheet surface of FIG. 2 , and in a direction parallel to the sheet surface of FIG. 3 ).
- connection holes 111 for connecting one ends of the pressure chambers 110 to the respective nozzles 8 a , 8 b and connection holes 112 for connecting the other ends of the pressure chambers 110 to a manifold passage 115 are formed so as to be arranged in a row along the longitudinal direction of the ink-jet head 10 .
- connection holes 113 for connecting one ends of the pressure chambers 110 to the respective nozzles 8 a , 8 b are formed.
- a manifold passage 115 for supplying ink to the pressure chambers 110 is formed in the manifold plate 25 .
- the manifold passage 115 is formed in a lower portion of the row constituted by the plurality of pressure chambers 110 to extend along the row direction.
- One end of the manifold passage 115 is connected to a non-illustrated ink supply source.
- the nozzles 8 a , 8 b are formed in the nozzle plate 26 .
- a large number of the individual ink flow paths 120 are formed so as to be arranged in the extending direction of the ink-jet head 10 .
- Each of the individual ink flow paths 120 is formed to extend from the manifold passage 115 through the connection hole 112 , the pressure chamber 110 , the connection hole 111 , and the connection hole 113 to extend to the nozzles 8 a , 8 b .
- the nozzles 8 a , 8 b are both formed to be tilted from a direction perpendicular to the surface of the nozzle plate 26 , and the tilt angle of the nozzle 8 a is different from the tilt angle of the nozzle 8 b .
- the tilt angles of the nozzles 8 a , 8 b with respect to the direction perpendicular to the surface of nozzle plate 26 may be from 30 to 60 degrees.
- the nozzle 8 a is formed so that a linear trajectory (first trajectory) 101 of the main droplet 61 and a linear trajectory (third trajectory) 103 of the satellite droplet 63 are substantially perpendicular to the surface of the paper 41 .
- the nozzle 8 b is formed so that a linear trajectory (second trajectory) 102 of the main droplet 62 intersects the trajectory 101 at a intersection point X between the nozzle 8 a , 8 b and the paper 41 (see FIGS. 1 and 2 ). It is considered that trajectory 101 is on the central axis of the nozzle 8 b , and that the trajectory 102 is on the central axis of the nozzle 8 b .
- a recess to which the edge of the projection 10 a communicating with an ink catching section 30 is fitted, is formed so as to extend in the longitudinal direction of the ink-jet head 10 . In the bottom surface of the recess, a large number of holes are formed for communicating with the manifold passage 115 .
- the projection 10 a includes a capillary ink flow path 10 b having a L-shaped form and formed to extend from one end through the other end of the projection 10 a in the widthwise direction thereof.
- a large number of the capillary ink flow paths 10 b are arranged in a row along the longitudinal direction of the projection 10 a .
- the hole formed in the bottom surface of the recess for communicating with the manifold passage 115 and one end of the capillary ink flow path 10 b are connected to each other.
- the ink catching section 30 is formed in an open end of the capillary ink flow path 10 b , which is disposed on a side opposite to the one end.
- the ink catching section 30 is arranged in a trajectory 104 of the united droplet 64 between the paper 41 and the intersection point X, and the ink catching section 30 catches or receives the united droplet 64 flying in the trajectory 104 .
- a lower edge portion and an upper edge portion of the ink catching section 30 protrude toward the nozzles 8 a , 8 b , with the lower edge portion protruding more prominently toward the side of nozzles 8 a , 8 b compared with the upper edge portion.
- the protruded area serves as an area for receiving the united droplet 64 .
- the capillary ink flow path 10 b sucks up and delivers the ink of united droplet 64 to the manifold passage 115 .
- the capillary ink flow path 10 b may be arranged so that the ink, which has been sucked, is discharged to another discharge position which is prepared separately.
- the actuator 21 is arranged to correspond to the associated pressure chamber 110 and has a stacked structure in which an individual electrode 35 and a piezoelectric sheet 37 are stacked in layers.
- the piezoelectric sheet 37 is formed of a ceramic material based on lead zirconate titanate (PZT) having ferroelectricity, and the lower sheet of the piezoelectric sheet 37 is adjacent to the actuator plate 22 which serves as an upper wall of the pressure chamber 110 .
- the actuator plate 22 is always kept at the ground potential, and functions as a common electrode which is common to the large number of ink ejecting sections 100 .
- the individual electrode 35 has a surface shape which is same as that of the piezoelectric sheet 37 (see FIG. 1 ).
- the individual electrode 35 is formed of a material based, for example, on Ag—Pd, and is connected to a non-illustrated flexible wiring board.
- the control device 20 is capable of controlling a drive pulse signal to be supplied to the individual electrode 35 via the flexible wiring board.
- the piezoelectric sheet 37 is polarized in the thickness direction thereof. Accordingly, when the control device 20 applies a potential higher than the ground potential to the individual electrode 35 , an electric field is applied to the piezoelectric sheet 37 in the polarization direction thereof. When the electric field is applied to the piezoelectric sheet 37 , a portion thereof, to which the electric field is applied, functions as an active portion and expands in the thickness direction thereof and at the same time, attempts to contract in the plane direction thereof by a transversal piezoelectric effect. Accompanying this phenomenon, the piezoelectric sheet 37 and the actuator plate 22 deform so as to project toward the pressure chamber 110 (a unimorph deformation). That is, a drive mechanism of unimorph type is realized in the actuator 21 .
- FIG. 4 shows a sectional view of nozzles 8 a , 8 b
- FIG. 4B shows an outline view of the nozzles 8 a , 8 b viewed from an ink ejection surface (viewed from the side of ink ejection ports of nozzles 8 a , 8 b ).
- the ejection ports of nozzles 8 a , 8 b have a circular shape and are formed in a same plane.
- a linear distance L 1 from the ejection port of nozzle 8 a to an intersection point X is longer than a liner distance L 2 from the ejection port of nozzle 8 b to the intersection point X.
- a diameter D 1 which is a diameter of the ejection port of nozzle 8 a is smaller than a diameter D 2 which is a diameter of the ejection port of nozzle 8 b .
- a dimension of opening of the ejection port of nozzle 8 a is smaller than a dimension of opening of the ejection port of nozzle 8 b .
- the ejection characteristics of ink droplet when a same ejection pressure is applied thereto, are follows: as the opening dimension of ejection port is smaller, the ejection speed of ink droplet becomes grater, and as the opening dimension of ejection port is greater, the ejection speed of ink droplet becomes smaller. Namely, in this embodiment, an ejection speed V 1 of a main droplet 61 in the nozzle 8 a is greater than an ejection speed V 2 of a main droplet 62 in the nozzle 8 b .
- FIG. 5 shows a sectional view of the ink ejecting section 100 when the control device drives the actuator 21 .
- FIG. 6 ( FIGS. 6A to 6 C) is a diagram showing states in which ink droplets are ejected from the nozzle 8 a .
- the control device 20 applies a predetermined potential to the individual electrode 35 in advance so that the-actuator 21 and the actuator plate 22 adjacent thereto swell into (deform to project toward) the pressure chamber 110 .
- the control device 20 lowers the potential applied to the ground potential once so that the actuator 21 and the actuator plate 22 adjacent thereto have a flat shape (see FIG. 3 ). After that, the control device applies the predetermined potential to the actuator 21 and the actuator plate 22 adjacent thereto again in a predetermined timing so that the actuator 21 and the actuator plate 22 adjacent thereto swell into the pressure chamber 110 .
- the control device 20 makes the volume of the pressure chamber 110 reverse back from the decreased state to the state prior to the volume has been decreased, thereby generating a negative pressure within the pressure chamber 110 , which in turn causes the pressure chamber 110 suck up the ink from the manifold passage 115 . Further, the control 20 decreases the volume of the pressure chamber once again, thereby generating a positive pressure within the pressure chamber 110 , which in turn causes the ink in the pressure chamber 110 to be ejected from the nozzle 8 a , 8 b simultaneously. Namely, this means that the control device 20 applies a drive pulse signal of square-wave to the individual electrode 35 so as to eject the ink droplets simultaneously from the nozzles 8 a , 8 b .
- a pulse width of the drive pulse is an AL (Acoustic Length) that is a time length required for a pressure wave to propagate from the manifold passages 115 toward the nozzles 8 a , 8 b in the pressure chamber 110 , and when the interior of the pressure chamber 110 is reversed from the negative-pressure state to the positive-pressure state, the positive pressures and the negative pressure are superimposed on each other. Accordingly, it is possible to make the nozzles 8 a , 8 b to simultaneously eject the ink droplets therethrough by a strong pressure.
- AL Acoustic Length
- whether or not a satellite droplet 63 is ejected depends on the ejection speed.
- the ejection speed of ink droplet is less than 4.5 m/sec and less than 7.0 m/sec.
- the ejection speed of ink droplet is not less than 4.5 m/sec and less than 7.0 m/sec, a desired satellite droplet 63 is ejected, as shown in FIG. 6B .
- the satellite droplet 63 flies so as to follow a main droplet 61 in a trajectory same as that of a main droplet 61 and at a speed lower than that of the main droplet 61 .
- the ejection speed of ink droplet is more than 7.0 m/sec, a large number of unstable satellite droplets are ejected.
- control device 20 performs control so that the ejection speed of ink droplet from the nozzle 8 a is not less than 4.5 m/sec and less than 7.0 m/sec and the ejection speed of ink droplet from nozzle 8 b is less than 4.5 m/sec.
- this ejection speed of ink droplet is determined, for example, by a voltage applied to the individual electrode 35 and a pulse width in addition to the dimension of opening of the nozzles.
- FIG. 7 FIGS. 7A to 7 D showing a sectional view illustrating states of ink droplets being ejected from the ink ejecting section 100 in chronological order.
- the control device 20 supplies a drive pulse signal to the actuator 21 , thereby driving the actuator 21 .
- a main droplet 61 is ejected from the nozzle 8 a along a trajectory 101 at an ejection speed V 1 and a satellite droplet 63 is ejected along a trajectory 103 at an ejection speed V 4 slower than the ejection speed V 1 .
- a main droplet 62 is ejected from the nozzle 8 b along a trajectory 102 at an ejection speed V 2 .
- the main droplets 61 , 62 are collided at an intersection point X to form a united droplet 64 .
- This united droplet 64 flies at a speed V 3 along a trajectory 104 , which is a new, linear trajectory and is different from the trajectory 101 .
- the satellite droplet 63 flies after or behind the main droplet 61 which has been ejected from the nozzle 8 a , and thus the satellite droplet 63 keeps flying at the ejection speed V 4 without colliding with the main droplet 62 .
- the united droplet 64 lands on an ink catching section 30 and the satellite droplet 63 lands on a paper 41 .
- the united droplet 64 which has landed on the ink catching section 30 , blends with ink held in the ink catching section 30 , is sucked up by a capillary ink passage 10 b , and is delivered to the manifold passage 115 through the capillary ink passage 10 b .
- the satellite droplet 63 has landed on the paper 41 , it forms a dot on the paper 41 .
- trajectory 103 of the satellite droplet 63 ejected from the nozzle 8 a is substantially perpendicular to the paper 41 . Accordingly, it is possible to form a circular dot on the paper 41 , thereby improving the print quality.
- the ejection ports of the nozzles 8 a , 8 b are formed in a same plane in the nozzle plate 26 , it is possible to form the nozzles 8 a , 8 b by a simple processing method of drilling through the nozzle 26 a , thereby reducing the manufacturing cost of the ink-jet head 10 .
- the linear distance L 1 from the ejection port of the nozzle 8 a to the intersection point X is longer than the liner distance L 2 from the ejection port of the nozzle 8 b to the intersection point X, and the diameter D 1 of the ejection port of nozzle 8 a is smaller than the diameter D 2 of the ejection port of nozzle 8 b .
- the ink catching section 30 which receives the united droplet 62 is provided to prevent the united droplet 64 from landing on the paper 41 . Further, the united droplet 64 received by the ink catching section 30 is supplied to the manifold passage 115 through the capillary ink passage 10 b to be recycled. Accordingly, the ink is not wasted and the running cost is reduced. Furthermore, since the capillary ink passage 10 b sucks up the ink by capillary force, it is possible to easily realize the foregoing constitution.
- the nozzles 8 a , 8 b are constituted so as to be formed in a same plane in the nozzle plate 26 , the constitution of the nozzles 8 a , 8 b is not limited to such an arrangement. For example, as shown in FIG.
- a nozzle plate 26 ′ may be formed so that a perpendicular direction with respect to a plane, in which an ejection port of a nozzle 8 a ′ is formed, is along a trajectory 101 ′ of a main droplet 61 , and a perpendicular direction with respect to a plane, in which an ejection port of a nozzle 8 b ′ is formed, is along a trajectory 102 ′ of a main droplet 63 .
- the plane of the nozzle 8 a ′ is parallel to the paper 41 .
- the ejection ports of nozzles 8 a ′, 8 b ′ have a circular shape, and a linear distance L 1 ′ from the ejection port of nozzle 8 a ′ to the intersection point X′, at which the trajectories 101 ′ and 102 ′ intersect with each other, is longer than a linear distance L 2 ′ from the ejection port of nozzle 8 b ′ to the intersection point X 1 .
- a diameter D 1 ′ of the nozzle 8 a ′ is smaller than a diameter D 2 ′ of the nozzle 8 b ′.
- a dimension of the ejection port of nozzle 8 a ′ is smaller than a dimension of the ejection port of nozzle 8 b′.
- nozzles 8 a ′, 8 b ′ so as to stabilize the ejection characteristics and to eject the main droplets 61 , 62 and the satellite droplet 63 with high precision.
- the second embodiment is same as the first embodiment except for the form of the nozzles. Accordingly, the remaining members or components are denoted with the same reference numerals as those of the first embodiment, omitting the explanation on these members or components.
- FIG. 9 shows a sectional view of the nozzles 8 a A, 8 b A
- FIG. 9B shows an outline view of the nozzles 8 a A, 8 b A viewed from the ink ejection surface.
- the nozzles 8 a A, 8 b A eject ink droplets on the basis of control of the control device 20 .
- the control device 20 performs control, in accordance with one ink ejection signal given to the actuator 21 , so that the nozzle 8 a A ejects a main droplet (first main droplet) 61 A having a relatively large diameter and a satellite droplet 63 A which is smaller in volume than the main droplet 61 A (for example, a volume of about 0.002 to 0.5 pl) together with the ejection of the main droplet 61 A, and at the same time, the nozzle 8 b A ejects only one main droplet (second main droplet) 62 A, and the main droplet 61 A ejected from the nozzle 8 a A and the main droplet 62 A ejected from the nozzle 8 b A collide with each other to form a united droplet 64 A which has a trajectory different from that of the main droplet 61 A (see FIG. 11 ).
- the nozzle 8 a A is formed so that a liner trajectory (first trajectory) 101 A is substantially perpendicular to the paper 41 .
- the nozzle 8 b A is formed so that a liner trajectory (second trajectory) 102 A intersects the trajectory 101 A at an intersection point XA between the nozzles 8 a A, 8 b A and the paper 41 (See FIGS. 11A and 11B ).
- the ejection port of nozzle 8 a A and the ejection port of nozzle 8 b A have a circular shape and are formed in a same plane. Further, a linear distance from the ejection port of nozzle 8 a A to the intersection point XA and a liner distance from the ejection port of nozzle 8 b A to the intersection point XA are same (reference numeral “L” in FIG. 9A ). In addition, as shown in FIG. 9B , a diameter of the ejection port of nozzle 8 a A and a diameter of the ejection port of nozzle 8 b A are same (reference numeral “D” in FIG. 9B ).
- a notched portion 81 is formed extending in a line which connects the nozzles 8 b A and 8 a A. Since the dimension of the notched portion 81 is very small, a dimension of an opening of the ejection port of nozzle 8 a A and a dimension of an opening of the ejection port of nozzle 8 b A are substantially same, and consequently an ejection speed at which a main droplet is ejected from the nozzle 8 a A and an ejection speed at which a main droplet is ejected from the nozzle 8 b A are substantially same.
- the main droplets 61 A, 62 A are ejected simultaneously and substantially in a linear trajectory. Consequently, the main droplet ejected from the nozzle 8 a A and the main droplet ejected from the nozzle 8 b A collide with each other at the intersection point XA.
- FIG. 10 FIGS. 10A to 10 D showing a state in which ink droplets are ejected from the nozzle 8 b A at about 6.0 m/sec.
- the method for driving the actuator 21 and the ink ejection operation from the nozzle 8 b A are same as those in the first embodiment, the detailed explanation thereon are omitted.
- the control device 20 supplies a drive pulse signal to the actuator 21 , thereby driving the actuator 21 to begin the ejection of main ink droplet 61 A, and ink is pushed out from the nozzle 8 a A as shown in FIG. 10A .
- the ink which has been pushed out from the nozzle 8 a A, is pulled slightly toward the notched portion 81 .
- the ink which is pushed out further, forms an ink droplet in a state with a tailing portion thereof being pulled toward the notched portion 81 .
- FIG. 10D the ink droplet, which has been formed in FIG.
- the satellite droplet 63 A is separated into a leading portion and a tailing portion wherein the leading portion forms a main droplet 61 A and the tailing portion forms a satellite droplet 63 A.
- the main droplet 61 A flies along a trajectory 101 A.
- the satellite droplet 63 A due to the force of inertia generated when the tailing portion has been pulled toward the side of the notched portion 81 , the satellite droplet 63 A flies along a trajectory (third trajectory) 103 A which is tilted toward the notched portion 81 as compared with the trajectory 101 A (see FIG. 11 ).
- FIG. 11 FIGS. 11A to 11 D showing a sectional view illustrating states of ink droplets ejected from the ink ejecting section 100 A in chronological order.
- the control device 20 supplies a drive pulse signal to the actuator 21 , thereby driving the actuator 21 .
- a main droplet 61 A is ejected from the nozzle 8 a A along a trajectory 101 A at an ejection speed V and a satellite droplet 63 A is ejected along a trajectory 103 A at an ejection speed V 4 lower than the ejection speed V.
- a main droplet 62 A is ejected along a trajectory 102 A at the ejection speed V.
- the main droplets 61 A and 62 A collide with each other at an intersection point XA to form a united droplet 64 A.
- This united droplet 64 flies at an ejection speed V 3 A along a new linear trajectory 104 A which is different from the trajectory 101 A.
- the satellite droplet 63 A does not pass through the intersection point XA because the satellite droplet 63 A flies along the trajectory 103 A different from the trajectory 101 A. Accordingly, the satellite droplet 63 A keeps flying at the speed V 4 without colliding with the main droplet 62 A ejected from the nozzle 8 b A. Subsequently, as shown in FIG. 1C , the united droplet 64 lands on the ink catching section 30 , and the satellite droplet 63 A lands on the paper 41 . Then, as shown in FIG.
- the united droplet 64 A which has landed on the ink catching section 30 , blends with ink held in the ink catching section 30 , is sucked up by the capillary ink passage 10 b , and is delivered to the manifold passage 115 from the capillary ink passage 10 b .
- the satellite droplet 63 which has landed on the paper 41 , becomes a dot on the paper 41 .
- the second embodiment it is possible to reliably prevent the satellite droplet 63 A from colliding with the main droplet 62 A because the satellite droplet 63 A will not pass through the intersection point XA due to the presence of the notched portion 81 . Accordingly, it is possible to eject the satellite droplet 63 A having a small volume of 0.002 to 0.5 pl to be reliably landed on the paper 41 .
- the present invention is not limited to the foregoing embodiments and many alternatives, modifications and variations in the constitution or design are possible.
- these trajectories 101 , 103 may be tilted with respect to the paper 41 .
- the actuator 21 of unimorph type may have constitution of, for example, a stacked type piezoelectric actuator and an electrostatic actuator.
- the invention may be applied to an ink-jet head based on the thermal system.
- the ink-jet head is constituted as a line head.
- the ink-jet head may be a serial head.
- the ink-jet head may be controlled so that the ink-jet head reciprocates in a direction perpendicular to a direction in which the paper 41 is transported. With this, it is possible to perform printing on a paper of a larger size with a shorter head.
- the united droplets 64 , 64 A land on the ink catching section 30 .
- the ink catching section 30 may be omitted and the united droplet is allowed to land on the paper 41 .
- the landed united droplet may be used not as information to be recorded (for example, used for background printing or printing on paper margin).
- a conductive paste may be used as the ejection medium. Accordingly, it is possible to print a very fine electric circuit pattern.
- an organic illuminant may be used as the ejection medium, thereby making it possible to make a high-resolution display devices such as an organic electroluminescence display (OELD).
- OELD organic electroluminescence display
- an ejection medium of other type may be used.
- the ejection speed of the satellite droplet is lower than the ejection speed of the main droplet.
- a phenomenon that the ejection speed of the satellite droplet becomes faster than the ejection speed of the main droplet may also be applied to the present invention.
- the satellite droplets 63 , 63 A are ejected from the nozzles 8 a , 8 a A, respectively, while no satellite droplet is ejected from the nozzles 8 b , 8 b A.
- the present invention is not limited to these constitutions, and the satellite droplet may be ejected also from the nozzle 8 b ( 8 b A).
- the catching section 30 is constituted so that the satellite droplet ejected from the nozzle 8 b ( 8 b A) can be caught in the catching section, or a dedicated catching section 30 for catching the satellite droplet ejected from the nozzle 8 b ( 8 b A) is separately provided.
- control may be performed so that the satellite droplet is ejected prior to the ejection of the main droplet.
Abstract
Description
- 1. Field of the Invention
- The present invention relates to an apparatus for ejecting droplets such as an ink-jet printer capable of ejecting very small droplets.
- 2. Description of the Related Art
- In ink-jet printers, it is desired that each ink droplet to be ejected from a printing head is as small as possible in order to improve print quality. From this viewpoint, an existing ink-jet printing head is capable of ejecting small ink droplets of about 2 pico-liter (pl) by, for example, modifying a control pulse waveform for an actuator to apply ejection energy to ink, or decreasing the diameter of each nozzle.
- In recent years, however, it is required to eject very small ink droplets of less than 2 pl to realize higher-quality, higher-resolution print. By the above-described technique of modifying a control pulse waveform or decreasing the diameter of each nozzle, however, it is difficult to further decrease the size of each ink droplet.
- Other than the above-described techniques, there is known a technique to regulate a control pulse waveform and, at the same time, to regulate a distance between the nozzle and a print medium such that a main dot (a main ink droplet) and a satellite dot (a satellite ink droplet), both of which are ejected through a nozzle in accordance with one pressure variation, may have substantially the same volume and such that landing positions of those two ink droplets may be different from each other (see Japanese Patent Application Laid-open No. 7-285222 (
FIG. 1 )). By this technique, the size of the main ink droplet can be decreased, besides the satellite ink droplet can be increased in size and thus this can be a dot independent of the main dot. - However, for printing an image at a very high resolution having, e.g., photographic quality, it is required to eject ink droplets each smaller than those obtained by the above-described technique. In addition to the requirement of ejecting very small ink droplets, there is a requirement for an ink-jet printer to eject very small droplets of conductive paste so that a very fine electric circuit on a substrate can be printed.
- U.S. Patent Application Publication No. U.S. 2004/0046825 A1, disclosed by the inventor, discloses an apparatus for ejecting very small droplets to form dots on a print medium, the apparatus characterized by including: a first droplet ejector capable of ejecting a first main droplet in a first trajectory and a satellite droplet smaller in volume than the first main droplet, the satellite droplet being ejected together with the first main droplet; a second droplet ejector capable of ejecting a droplet having a second trajectory intersecting the first trajectory; and a control unit for controlling the first and second droplet ejectors so that the first main droplet and the droplet ejected from the second droplet ejector collide to unite with each other and a united droplet flies in a trajectory different from the first trajectory and the satellite droplet lands on the print medium. In this apparatus, actuators are separately provided to drive the first and second droplet ejectors.
- U.S. Pat. No. 6,167,748 (corresponding to Japanese Patent Application Laid-open No. 11-99651) discloses a liquid discharge method and apparatus which enables, for example, a gradation recording by ejecting two droplets respectively from first and second discharge ports and by colliding these droplets to unite with each other while these droplets are flying. The first and second discharge openings are provided with first and second flow paths which communicate therewith respectively, and first and second energy generating devices for discharging the droplets therefrom respectively. On the other hand, Japanese Patent Application Laid-open No. 2001-239681 discloses that a plurality of droplets discharged from a plurality of nozzles are made to unite with each other to land on a recording paper. Each of the plurality of nozzles communicates with a flow path provided with a heater.
- A main object of the present invention is to provide an apparatus for ejecting droplets capable of ejecting very small droplets.
- According to a first aspect of the present invention, there is provided an apparatus for ejecting droplets to form dots on a medium, the apparatus comprising: an ejection pressure applying section which applies ejection pressure to a storage chamber which stores liquid; a first nozzle which communicates with the storage chamber and which ejects a first main droplet in a first trajectory together with a satellite droplet having a volume smaller than the first main droplet; a second nozzle which communicates with the storage chamber and which ejects a second main droplet in a second trajectory intersecting the first trajectory at a predetermined intersection point; a control device which controls the ejection pressure applying section; and a medium holding device which holds the medium; wherein the control device controls the ejection pressure applying section so that the first main droplet and the second main droplet collide with each other at the intersection point to form a united droplet, and the satellite droplet, which has been ejected from the first nozzle, lands on the medium.
- According to a second aspect of the present invention, there is provided an apparatus for ejecting droplets to form dots on a medium, the apparatus comprising: an ejection pressure applying section which applies ejection pressure to a storage chamber which stores liquid; a first nozzle which communicates with the storage chamber and which ejects a first main droplet in a first trajectory; a second nozzle which communicates with the storage chamber and which ejects a second main droplet in a second trajectory intersecting the first trajectory at a predetermined intersection point; a control device which controls the ejection pressure applying section so as to eject from the first nozzle the first main droplet and a satellite droplet which has a volume smaller than the first main droplet and which flies apart from the first main droplet, and to eject from the second nozzle the second main droplet which collides with the first main droplet at the intersection point to form a united droplet; and a print medium holding device which holds the medium at a position intersecting a trajectory of the satellite droplet.
- According to the present invention, it is possible to make the satellite droplet (very small droplet), ejected together with the first main droplet and having a volume smaller than the first main droplet, land on the medium in order to form a very small dot. In addition, it is possible to constitute a droplet ejecting apparatus which allows the very small droplet to land on the medium with only one ejection pressure applying section. Accordingly, such an apparatus can be realized at a low cost.
- In the present invention, a flying direction of the united droplet may be different from a flying direction of the satellite droplet ejected from the first nozzle. Accordingly, it is possible to form a dot on the medium only with the satellite droplet, without making the united droplet land on the medium.
- In the present invention, a volume of the satellite droplet may be 0.002 to 0.5 pl. By adjusting the volume of the satellite droplet to this volume, it is possible to form an even smaller dot on the medium.
- In the present invention, the first trajectory may be perpendicular to a surface of the medium held in the medium holding device. Accordingly, it is possible to form a circular dot on the medium, thereby improving the image quality.
- In the present invention, an ejection port of the first nozzle and an ejection port of the second nozzle may be formed in a same plane. Accordingly, it is possible to easily form the first nozzle and the second nozzle, thereby decreasing the cost for manufacturing the droplet ejecting apparatus.
- In the present invention, a first plane in which an ejection port of the first nozzle is formed and a second plane in which the second nozzle is formed may be planes intersecting with each other; and the first nozzle may be formed so that an axis line of the first nozzle extends along the first trajectory, and the second nozzle may be formed so that an axis line of the second nozzle extends along the second trajectory. Accordingly, it is possible to form the first nozzle and the second nozzle so that the ejection characteristics are stabilized and the satellite droplet, the first and second main droplets are ejected with high precision.
- In addition, in the present invention, a nozzle diameter of the first nozzle at an ejection port thereof and a nozzle diameter of the second nozzle at an ejection port thereof may be different. Accordingly, it is possible to prevent the second nozzle from ejecting excess satellite droplets, thereby preventing the inconvenience that the medium is stained with the excess satellite droplets.
- Further, in the present invention, a nozzle diameter of the first nozzle at an ejection port thereof may be smaller than a nozzle diameter of the second nozzle at an ejection port thereof; and a linear distance between the ejection port of the first nozzle and the intersection point may be longer than a linear distance between the ejection port of the second nozzle and the intersection point. Accordingly, it is possible to eject the satellite droplet from the first nozzle, to prevent the second nozzle from ejecting any satellite droplet, and to make the first main droplet and the second main droplet collide with each other.
- Furthermore, in the present invention, a following expression may be held when the control device drives the ejection pressure applying section: L1/V1=L2/V2; wherein L1 is a linear distance between an ejection port of the first nozzle and the intersection point; L2 is a linear distance between an ejection port of the second nozzle and the intersection point; V1 is an ejection speed of the first main droplet ejected from the first nozzle; and V2 is an ejection speed of the second main droplet ejected from the second nozzle. Accordingly, it is possible to ensure that the first and second main droplets collide with each other.
- In the present invention, an ejection speed of the first main droplet ejected from the first nozzle may be not less than 4.5 m/sec and less than 7.0 m/sec; and an ejection speed of the second main droplet ejected from the second nozzle may be less than 4.5 m/sec. Accordingly, it is possible for the first nozzle to eject a desired satellite droplet, and for the second nozzle not to eject any satellite droplet.
- In the present invention, an ejection port of the first nozzle may have a circular or elliptic shape; and a trajectory of the satellite droplet may be same as the first trajectory. Accordingly, it is possible to eject the satellite droplet with high precision.
- In the present invention, an ejection port of the first nozzle may have a circular or elliptic shape in which a notch is formed in a portion of outer edge thereof; and a trajectory of the satellite droplet may be tilted toward the notch from the first trajectory. Accordingly, the satellite droplet and the second main droplet hardly collide with each other, because the satellite droplet will not pass through the intersection point.
- In the present invention, a droplet catching section for catching the united droplet may be disposed in a trajectory of the united droplet. Accordingly, the united droplet will never land on the medium and thus no excessive dots will be formed.
- In the present invention, the apparatus may further comprise a discharge passage for discharging the united droplet which has been caught in the droplet catching section. Accordingly, it is possible to discharge the liquid held by the droplet catching section, thereby decreasing the volume of the droplet catching section.
- In the present invention, the apparatus may further comprise a liquid chamber for supplying the liquid to the storage chamber; and a delivery passage for delivering the united droplet which has been caught in the droplet catching section to the liquid chamber. Accordingly, it is possible to recycle the united droplet and thus reduce the running cost.
- In the present invention, the delivery passage may suck up the united droplet to the liquid chamber by capillary force. Accordingly, it is possible to suck up the united droplet with a simple constitution with high efficiency.
- According to a third aspect of the present invention, there is provided a droplet-ejecting head which forms dots on a medium, the droplet-ejecting head comprising: an ejection surface in which a first nozzle and a second nozzle are formed, the second nozzle having an ejection direction different from an ejection direction of the first nozzle; a pressure chamber which is common to the first nozzle and the second nozzle, and which stores liquid to be ejected from the first nozzle and the second nozzle; and an actuator which applies ejection pressure to the pressure chamber. Since this droplet-ejecting head includes a pressure chamber and an actuator common to the first nozzle and the second nozzle, it is possible to practice the printing method as disclosed in U.S. Patent Application Publication No. U.S. 2004/0046825 A1 with a much simpler construction. The first and second nozzles may be formed to be tilted from a direction perpendicular to a surface of a nozzle plate. In addition, a nozzle diameter of the first nozzle may be different from a nozzle diameter of the second nozzle.
-
FIG. 1 shows a perspective view illustrating a schematic arrangement of an ink-jet printer including an ink ejecting section according to a first embodiment of the present application. -
FIG. 2 shows a sectional view illustrating the ink ejecting section shown inFIG. 1 . -
FIG. 3 shows a sectional view illustrating the ink ejecting section taken along a line III-III shown inFIG. 2 . -
FIGS. 4A and 4B show a magnified view of nozzles shown inFIG. 3 . -
FIG. 5 shows a sectional view of an actuator in the ink ejecting section shown inFIG. 1 , when the actuator is driven. -
FIGS. 6A to 6C are diagrams respectively illustrating states of ink droplets ejected from the nozzle shown inFIG. 3 . -
FIG. 7A shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown inFIG. 1 in chronological order. -
FIG. 7B shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown inFIG. 1 in chronological order. -
FIG. 7C shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown inFIG. 1 in chronological order. -
FIG. 7D shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown inFIG. 1 in chronological order. -
FIGS. 8A and 8B show sectional views illustrating a modification of the nozzles shown inFIG. 2 . -
FIGS. 9A and 9B show magnified views of nozzles of an ink ejecting section according to a second embodiment of the present application. -
FIGS. 10A to 10D show sectional views illustrating an operation in which ink droplets are ejected from the nozzle shown inFIG. 9 . -
FIG. 11A shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown inFIG. 9 in chronological order. -
FIG. 11B shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown inFIG. 9 in chronological order. -
FIG. 11C shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown inFIG. 9 in chronological order. -
FIG. 11D shows a sectional view illustrating a state of ink droplets ejected from the ink ejecting section shown inFIG. 9 in chronological order. - A first embodiment of the present invention will be explained with reference to the drawings.
FIG. 1 shows a perspective view illustrating a schematic arrangement of an ink-jet printer including an ink ejecting section according to the first embodiment. For sake of explanation,FIG. 1 shows the ink-jet printer in a state in which a part of the printer is cut open. As shown inFIG. 1 , an ink-jet printer 1 includes thereinplaten rollers paper 41 as a medium and as a medium holding means (device) which holds thepaper 41 at a recording position; guiderollers paper 41 therebetween together with theplaten rollers jet head 10 which ejects ink droplets onto thepaper 41 transported by the transport means; and acontrol device 20. - The
platen rollers platen rollers electric motor 44 to rotate. Thepaper 41 is fed from a non-illustrated paper feed cassette provided in one side portion of the ink-jet printer 1. Thepaper 41 is then transported by theplaten rollers paper 41 with ink ejected from the ink-jet head 10, thepaper 41 is discharged from the ink-jet printer 1. - In
FIG. 1 , a detailed illustration of the mechanism for feeding and discharging thepaper 41 is omitted. The ink-jet printer 1 ofFIG. 1 is a monochrome printer and thus includes only one ink-jet head 10. In the case a color printing is performed with the ink-jet printer 1, at least four ink-jet heads 10 for yellow, magenta, cyan, and black are provided in parallel. - The ink-
jet head 10 is a line head extending perpendicularly to the transport direction of thepaper 41. The ink-jet head 10 is fixed to the frame so as to oppose to thepaper 41 at a predetermined angle. A large number ofnozzles control device 20, are arranged in a row in an ink-ejection surface (lower surface) of the ink-jet head 10 along the longitudinal direction of the ink-jet head 10. In addition, thenozzles jet head 10. Thenozzle 8 a is formed so that the trajectory (first trajectory) of an ink droplet ejected from thenozzle 8 a is substantially perpendicular to thepaper 41, and thenozzle 8 b is formed so that the trajectory (second trajectory) of an ink droplet ejected from thenozzle 8 b intersect the trajectory of the ink droplet ejected from thenozzle 8 a at a predetermined angle. A large number ofactuators 21, which is controlled by thecontrol device 20 for makingnozzles jet head 10 along the longitudinal direction of the ink-jet head 10. In the ink-jet head 10, a large number ofink ejecting sections 100 are arranged along the extending direction of the ink-jet head 10. Each of theink ejecting sections 100 includes a pair ofnozzles ink flow path 120 which communicates with thenozzles actuator 21. In addition, in the ink-ejecting surface of the ink-jet head 10, aprojection 10 a is arranged. Theprojection 10 a extends along the extending direction of ink-jet head 10, and is an L-shaped in cross section in the widthwise direction thereof. - The
control device 20 controls the operations of parts or components of the ink-jet printer 1, such as theelectric motor 44 and the ink-jet head 10. Particularly in this embodiment, thecontrol device 20 perform control, in accordance with one ink ejection signal (which means a drive pulse corresponding to one dot on the paper 41), so that thenozzle 8 a ejects a main droplet (first main droplet) 61 having a relatively large diameter (for example, a diameter of about 4 to 25 μm) and asatellite droplet 63 which is smaller in volume than the main droplet 61 (for example, having a diameter of about 1.6 to 10 μm) after the ejection of themain droplet 61, and at the same time, thenozzle 8 b ejects only one main droplet (second main droplet) 62. It is considered that themain droplet 61 ejected from thenozzle 8 a and themain droplet 62 ejected from thenozzle 8 b collide with each other to form aunited droplet 64 which has a trajectory different from that of the main droplet 61 (seeFIG. 2 ). Further, the ejection speed and the volume of the ink droplets can be controlled by adjusting at least one of the pulse height, the number of pulses, the pulse width of the ink ejection signal or the like on the basis of the dimension of the ejection port ofnozzles - Next, an internal structure of the ink-
jet head 10 will be explained with reference toFIGS. 2 and 3 .FIG. 2 shows a sectional view illustrating theink ejecting section 100 in the ink-jet head 10.FIG. 3 shows a sectional view illustrating theink ejecting section 100 taken along a line III-III shown inFIG. 2 . As shown inFIGS. 2 and 3 , in the ink-jet head 10, anactuator 21, which is driven with a drive pulse signal (which can take selectively one of the ground potential and a predetermined positive potential) generated in a non-illustrated drive circuit, and aflow path unit 4 forming an individual ink flow path are stacked in layers. Theactuator 21 and flowpath unit 4 are bonded to each other with an epoxy-base thermo-curable adhesive. For applying the drive pulse signal generated in the non-illustrated driving circuit, a flexible printer wiring board (not illustrated) is bonded to the upper surface of theactuator 21. In addition, the ink-ejection surface of theflow path unit 4 is fitted with an edge of theprojection 10 a in a perpendicular direction. - The
flow path unit 4 is constructed by stacking in layers: four thin-shaped plates formed of a metal material (anactuator plate 22, acavity plate 23, asupply plate 24, and a manifold plate 25); and anozzle plate 26 which is formed of a synthetic resin such as polyimide and which includesnozzles actuator plate 22 in the uppermost layer is in contact with theactuator 21. - On the surface of the
cavity plate 23, a plurality ofpressure chambers 110 are formed for storing ink to be selectively ejected by an action of theactuator 21. Thepressure chambers 110 are arranged in a row along the longitudinal direction of the ink-jet head 10 (a direction perpendicular to the sheet surface ofFIG. 2 , and in a direction parallel to the sheet surface ofFIG. 3 ). - In the
supply plate 24, connection holes 111 for connecting one ends of thepressure chambers 110 to therespective nozzles connection holes 112 for connecting the other ends of thepressure chambers 110 to a manifold passage 115 (to be explained later) are formed so as to be arranged in a row along the longitudinal direction of the ink-jet head 10. - In the
manifold plate 25, connection holes 113 for connecting one ends of thepressure chambers 110 to therespective nozzles manifold plate 25, amanifold passage 115 for supplying ink to thepressure chambers 110 is formed. Themanifold passage 115 is formed in a lower portion of the row constituted by the plurality ofpressure chambers 110 to extend along the row direction. One end of themanifold passage 115 is connected to a non-illustrated ink supply source. - The
nozzles nozzle plate 26. Thus, in the ink-jet head 10, a large number of the individualink flow paths 120 are formed so as to be arranged in the extending direction of the ink-jet head 10. Each of the individualink flow paths 120 is formed to extend from themanifold passage 115 through theconnection hole 112, thepressure chamber 110, theconnection hole 111, and theconnection hole 113 to extend to thenozzles nozzles nozzle plate 26, and the tilt angle of thenozzle 8 a is different from the tilt angle of thenozzle 8 b. The tilt angles of thenozzles nozzle plate 26 may be from 30 to 60 degrees. Specifically, thenozzle 8 a is formed so that a linear trajectory (first trajectory) 101 of themain droplet 61 and a linear trajectory (third trajectory) 103 of thesatellite droplet 63 are substantially perpendicular to the surface of thepaper 41. Thenozzle 8 b is formed so that a linear trajectory (second trajectory) 102 of themain droplet 62 intersects thetrajectory 101 at a intersection point X between thenozzle FIGS. 1 and 2 ). It is considered thattrajectory 101 is on the central axis of thenozzle 8 b, and that thetrajectory 102 is on the central axis of thenozzle 8 b. In addition, in thenozzle plate 26, a recess, to which the edge of theprojection 10 a communicating with anink catching section 30 is fitted, is formed so as to extend in the longitudinal direction of the ink-jet head 10. In the bottom surface of the recess, a large number of holes are formed for communicating with themanifold passage 115. - The
projection 10 a includes a capillaryink flow path 10 b having a L-shaped form and formed to extend from one end through the other end of theprojection 10 a in the widthwise direction thereof. A large number of the capillaryink flow paths 10 b are arranged in a row along the longitudinal direction of theprojection 10 a. When theprojection 10 b is fitted to the recess formed in the ink-ejection surface of thenozzle plate 26, the hole formed in the bottom surface of the recess for communicating with themanifold passage 115 and one end of the capillaryink flow path 10 b are connected to each other. In an open end of the capillaryink flow path 10 b, which is disposed on a side opposite to the one end, theink catching section 30 is formed. - The
ink catching section 30 is arranged in atrajectory 104 of theunited droplet 64 between thepaper 41 and the intersection point X, and theink catching section 30 catches or receives theunited droplet 64 flying in thetrajectory 104. In thetrajectory 104, a lower edge portion and an upper edge portion of theink catching section 30 protrude toward thenozzles nozzles united droplet 64. When theink catching section 30 receives theunited droplet 64, the capillaryink flow path 10 b sucks up and delivers the ink ofunited droplet 64 to themanifold passage 115. The capillaryink flow path 10 b may be arranged so that the ink, which has been sucked, is discharged to another discharge position which is prepared separately. - The
actuator 21 is arranged to correspond to the associatedpressure chamber 110 and has a stacked structure in which anindividual electrode 35 and apiezoelectric sheet 37 are stacked in layers. Thepiezoelectric sheet 37 is formed of a ceramic material based on lead zirconate titanate (PZT) having ferroelectricity, and the lower sheet of thepiezoelectric sheet 37 is adjacent to theactuator plate 22 which serves as an upper wall of thepressure chamber 110. Theactuator plate 22 is always kept at the ground potential, and functions as a common electrode which is common to the large number ofink ejecting sections 100. Theindividual electrode 35 has a surface shape which is same as that of the piezoelectric sheet 37 (seeFIG. 1 ). In addition, theindividual electrode 35 is formed of a material based, for example, on Ag—Pd, and is connected to a non-illustrated flexible wiring board. Thecontrol device 20 is capable of controlling a drive pulse signal to be supplied to theindividual electrode 35 via the flexible wiring board. - The
piezoelectric sheet 37 is polarized in the thickness direction thereof. Accordingly, when thecontrol device 20 applies a potential higher than the ground potential to theindividual electrode 35, an electric field is applied to thepiezoelectric sheet 37 in the polarization direction thereof. When the electric field is applied to thepiezoelectric sheet 37, a portion thereof, to which the electric field is applied, functions as an active portion and expands in the thickness direction thereof and at the same time, attempts to contract in the plane direction thereof by a transversal piezoelectric effect. Accompanying this phenomenon, thepiezoelectric sheet 37 and theactuator plate 22 deform so as to project toward the pressure chamber 110 (a unimorph deformation). That is, a drive mechanism of unimorph type is realized in theactuator 21. - Next, the construction of the
nozzles FIG. 4 (FIGS. 4A and 4B ) showing a magnified view of thenozzles FIG. 4A shows a sectional view ofnozzles FIG. 4B shows an outline view of thenozzles nozzles FIG. 4A , the ejection ports ofnozzles nozzle 8 a to an intersection point X is longer than a liner distance L2 from the ejection port ofnozzle 8 b to the intersection point X. As shown inFIG. 4B , a diameter D1 which is a diameter of the ejection port ofnozzle 8 a is smaller than a diameter D2 which is a diameter of the ejection port ofnozzle 8 b. In other words, a dimension of opening of the ejection port ofnozzle 8 a is smaller than a dimension of opening of the ejection port ofnozzle 8 b. The ejection characteristics of ink droplet, when a same ejection pressure is applied thereto, are follows: as the opening dimension of ejection port is smaller, the ejection speed of ink droplet becomes grater, and as the opening dimension of ejection port is greater, the ejection speed of ink droplet becomes smaller. Namely, in this embodiment, an ejection speed V1 of amain droplet 61 in thenozzle 8 a is greater than an ejection speed V2 of amain droplet 62 in thenozzle 8 b. Further, in order to eject themain droplets main droplets - Next, the operation of
ink ejecting section 100 will be explained with reference toFIGS. 5 and 6 .FIG. 5 shows a sectional view of theink ejecting section 100 when the control device drives theactuator 21.FIG. 6 (FIGS. 6A to 6C) is a diagram showing states in which ink droplets are ejected from thenozzle 8 a. First, thecontrol device 20 applies a predetermined potential to theindividual electrode 35 in advance so that the-actuator 21 and theactuator plate 22 adjacent thereto swell into (deform to project toward) thepressure chamber 110. Then, every time thecontrol device 20 receives a command to perform ejection, thecontrol device 20 lowers the potential applied to the ground potential once so that theactuator 21 and theactuator plate 22 adjacent thereto have a flat shape (seeFIG. 3 ). After that, the control device applies the predetermined potential to theactuator 21 and theactuator plate 22 adjacent thereto again in a predetermined timing so that theactuator 21 and theactuator plate 22 adjacent thereto swell into thepressure chamber 110. - In this manner, the
control device 20 makes the volume of thepressure chamber 110 reverse back from the decreased state to the state prior to the volume has been decreased, thereby generating a negative pressure within thepressure chamber 110, which in turn causes thepressure chamber 110 suck up the ink from themanifold passage 115. Further, thecontrol 20 decreases the volume of the pressure chamber once again, thereby generating a positive pressure within thepressure chamber 110, which in turn causes the ink in thepressure chamber 110 to be ejected from thenozzle control device 20 applies a drive pulse signal of square-wave to theindividual electrode 35 so as to eject the ink droplets simultaneously from thenozzles manifold passages 115 toward thenozzles pressure chamber 110, and when the interior of thepressure chamber 110 is reversed from the negative-pressure state to the positive-pressure state, the positive pressures and the negative pressure are superimposed on each other. Accordingly, it is possible to make thenozzles - In this embodiment, whether or not a
satellite droplet 63 is ejected depends on the ejection speed. As an example, in a case an ink having a viscosity of 5 cp and a surface tension of 40 mN/M is ejected and when the ejection speed of ink droplet is less than 4.5 m/sec, nosatellite droplet 63 is ejected, as shown inFIG. 6A . On the other hand, when the ejection speed of ink droplet is not less than 4.5 m/sec and less than 7.0 m/sec, a desiredsatellite droplet 63 is ejected, as shown inFIG. 6B . At this time, thesatellite droplet 63 flies so as to follow amain droplet 61 in a trajectory same as that of amain droplet 61 and at a speed lower than that of themain droplet 61. This means that atrajectory 101 of themain droplet 61 and atrajectory 103 of thesatellite droplet 63 are same. However, when the ejection speed of ink droplet is more than 7.0 m/sec, a large number of unstable satellite droplets are ejected. As explained above, it is preferable in this embodiment that thecontrol device 20 performs control so that the ejection speed of ink droplet from thenozzle 8 a is not less than 4.5 m/sec and less than 7.0 m/sec and the ejection speed of ink droplet fromnozzle 8 b is less than 4.5 m/sec. As described above, this ejection speed of ink droplet is determined, for example, by a voltage applied to theindividual electrode 35 and a pulse width in addition to the dimension of opening of the nozzles. - Next, the operation of
ink ejecting section 100 will be explained in detail with reference toFIG. 7 (FIGS. 7A to 7D) showing a sectional view illustrating states of ink droplets being ejected from theink ejecting section 100 in chronological order. Thecontrol device 20 supplies a drive pulse signal to theactuator 21, thereby driving theactuator 21. As shown inFIG. 7A , amain droplet 61 is ejected from thenozzle 8 a along atrajectory 101 at an ejection speed V1 and asatellite droplet 63 is ejected along atrajectory 103 at an ejection speed V4 slower than the ejection speed V1. At the same time, only amain droplet 62 is ejected from thenozzle 8 b along atrajectory 102 at an ejection speed V2. As shown inFIG. 7B , themain droplets united droplet 64. Thisunited droplet 64 flies at a speed V3 along atrajectory 104, which is a new, linear trajectory and is different from thetrajectory 101. At this time, thesatellite droplet 63 flies after or behind themain droplet 61 which has been ejected from thenozzle 8 a, and thus thesatellite droplet 63 keeps flying at the ejection speed V4 without colliding with themain droplet 62. Then, as shown inFIG. 7C , theunited droplet 64 lands on anink catching section 30 and thesatellite droplet 63 lands on apaper 41. Subsequently, as shown inFIG. 7D , theunited droplet 64, which has landed on theink catching section 30, blends with ink held in theink catching section 30, is sucked up by acapillary ink passage 10 b, and is delivered to themanifold passage 115 through thecapillary ink passage 10 b. When thesatellite droplet 63 has landed on thepaper 41, it forms a dot on thepaper 41. - According to the first embodiment as explained above, it is possible to eject a
satellite droplet 63 having a small volume of 0.002 to 0.5 pl to be landed on thepaper 41, thereby making it possible to form a very small dot on thepaper 41. - Further, the
trajectory 103 of thesatellite droplet 63 ejected from thenozzle 8 a is substantially perpendicular to thepaper 41. Accordingly, it is possible to form a circular dot on thepaper 41, thereby improving the print quality. - Since the ejection ports of the
nozzles nozzle plate 26, it is possible to form thenozzles jet head 10. - In addition, the linear distance L1 from the ejection port of the
nozzle 8 a to the intersection point X is longer than the liner distance L2 from the ejection port of thenozzle 8 b to the intersection point X, and the diameter D1 of the ejection port ofnozzle 8 a is smaller than the diameter D2 of the ejection port ofnozzle 8 b. Further, the relationship of L1/V1=L2/V2 is held in which V1 is the ejection speed ofnozzle 8 a (not less than 4.5 m/sec and less than 7.0 m/sec) and V2 is the ejection speed ofnozzle 8 b (less than 4.5 m/sec). Accordingly, it is possible to eject the desiredsatellite droplet 63 from thenozzle 8 a, to eject only themain droplet 62 from thenozzle 8 b, and to ensure that themain droplets - The
ink catching section 30 which receives theunited droplet 62 is provided to prevent theunited droplet 64 from landing on thepaper 41. Further, theunited droplet 64 received by theink catching section 30 is supplied to themanifold passage 115 through thecapillary ink passage 10 b to be recycled. Accordingly, the ink is not wasted and the running cost is reduced. Furthermore, since thecapillary ink passage 10 b sucks up the ink by capillary force, it is possible to easily realize the foregoing constitution. - In the first embodiment, although the
nozzles nozzle plate 26, the constitution of thenozzles FIG. 8A , anozzle plate 26′ may be formed so that a perpendicular direction with respect to a plane, in which an ejection port of anozzle 8 a′ is formed, is along atrajectory 101′ of amain droplet 61, and a perpendicular direction with respect to a plane, in which an ejection port of anozzle 8 b′ is formed, is along atrajectory 102′ of amain droplet 63. At this time, the plane of thenozzle 8 a′ is parallel to thepaper 41. In addition, the ejection ports ofnozzles 8 a′, 8 b′ have a circular shape, and a linear distance L1′ from the ejection port ofnozzle 8 a′ to the intersection point X′, at which thetrajectories 101′ and 102′ intersect with each other, is longer than a linear distance L2′ from the ejection port ofnozzle 8 b′ to the intersection point X1. Further, as shown inFIG. 8B , a diameter D1′ of thenozzle 8 a′ is smaller than a diameter D2′ of thenozzle 8 b′. In other words, a dimension of the ejection port ofnozzle 8 a′ is smaller than a dimension of the ejection port ofnozzle 8 b′. - Accordingly, it is possible to form the
nozzles 8 a′, 8 b′ so as to stabilize the ejection characteristics and to eject themain droplets satellite droplet 63 with high precision. - Next, a second embodiment of the present invention will be explained with reference to the drawings. The second embodiment is same as the first embodiment except for the form of the nozzles. Accordingly, the remaining members or components are denoted with the same reference numerals as those of the first embodiment, omitting the explanation on these members or components.
- An explanation will be given regarding the arrangement of the nozzles according to the second embodiment with reference to
FIG. 9 (FIGS. 9A and 9B ) showing a magnified view of nozzles 8 aA, 8 bA of an ink ejecting section 10A.FIG. 9A shows a sectional view of the nozzles 8 aA, 8 bA, andFIG. 9B shows an outline view of the nozzles 8 aA, 8 bA viewed from the ink ejection surface. The nozzles 8 aA, 8 bA eject ink droplets on the basis of control of thecontrol device 20. - The
control device 20 performs control, in accordance with one ink ejection signal given to theactuator 21, so that the nozzle 8 aA ejects a main droplet (first main droplet) 61A having a relatively large diameter and asatellite droplet 63A which is smaller in volume than themain droplet 61A (for example, a volume of about 0.002 to 0.5 pl) together with the ejection of themain droplet 61A, and at the same time, the nozzle 8 bA ejects only one main droplet (second main droplet) 62A, and themain droplet 61A ejected from the nozzle 8 aA and themain droplet 62A ejected from the nozzle 8 bA collide with each other to form aunited droplet 64A which has a trajectory different from that of themain droplet 61A (seeFIG. 11 ). - The nozzle 8 aA is formed so that a liner trajectory (first trajectory) 101A is substantially perpendicular to the
paper 41. The nozzle 8 bA is formed so that a liner trajectory (second trajectory) 102A intersects thetrajectory 101A at an intersection point XA between the nozzles 8 aA, 8 bA and the paper 41 (SeeFIGS. 11A and 11B ). - As shown in
FIG. 9A , the ejection port of nozzle 8 aA and the ejection port of nozzle 8 bA have a circular shape and are formed in a same plane. Further, a linear distance from the ejection port of nozzle 8 aA to the intersection point XA and a liner distance from the ejection port of nozzle 8 bA to the intersection point XA are same (reference numeral “L” inFIG. 9A ). In addition, as shown inFIG. 9B , a diameter of the ejection port of nozzle 8 aA and a diameter of the ejection port of nozzle 8 bA are same (reference numeral “D” inFIG. 9B ). In an outer edge of the ejection port of nozzle 8 aA, a notchedportion 81 is formed extending in a line which connects the nozzles 8 bA and 8 aA. Since the dimension of the notchedportion 81 is very small, a dimension of an opening of the ejection port of nozzle 8 aA and a dimension of an opening of the ejection port of nozzle 8 bA are substantially same, and consequently an ejection speed at which a main droplet is ejected from the nozzle 8 aA and an ejection speed at which a main droplet is ejected from the nozzle 8 bA are substantially same. Themain droplets - Next, an ink ejection operation in the nozzle 8 aA will be explained with reference to
FIG. 10 (FIGS. 10A to 10D) showing a state in which ink droplets are ejected from the nozzle 8 bA at about 6.0 m/sec. The method for driving theactuator 21 and the ink ejection operation from the nozzle 8 bA are same as those in the first embodiment, the detailed explanation thereon are omitted. - The
control device 20 supplies a drive pulse signal to theactuator 21, thereby driving theactuator 21 to begin the ejection ofmain ink droplet 61A, and ink is pushed out from the nozzle 8 aA as shown inFIG. 10A . At this time, as shown inFIG. 10B , the ink, which has been pushed out from the nozzle 8 aA, is pulled slightly toward the notchedportion 81. Then, as shown inFIG. 10C , the ink, which is pushed out further, forms an ink droplet in a state with a tailing portion thereof being pulled toward the notchedportion 81. Subsequently, as shown inFIG. 10D , the ink droplet, which has been formed inFIG. 10C , is separated into a leading portion and a tailing portion wherein the leading portion forms amain droplet 61A and the tailing portion forms asatellite droplet 63A. Themain droplet 61A flies along atrajectory 101A. As for thesatellite droplet 63A, due to the force of inertia generated when the tailing portion has been pulled toward the side of the notchedportion 81, thesatellite droplet 63A flies along a trajectory (third trajectory) 103A which is tilted toward the notchedportion 81 as compared with thetrajectory 101A (seeFIG. 11 ). - Next, the operation of the ink ejecting section 100A will be explained in detail with reference to
FIG. 11 (FIGS. 11A to 11D) showing a sectional view illustrating states of ink droplets ejected from the ink ejecting section 100A in chronological order. Thecontrol device 20 supplies a drive pulse signal to theactuator 21, thereby driving theactuator 21. As shown inFIG. 11A , amain droplet 61A is ejected from the nozzle 8 aA along atrajectory 101A at an ejection speed V and asatellite droplet 63A is ejected along atrajectory 103A at an ejection speed V4 lower than the ejection speed V. At the same time, only amain droplet 62A is ejected along atrajectory 102A at the ejection speed V. Subsequently, as shown inFIG. 11B , themain droplets united droplet 64A. Thisunited droplet 64 flies at an ejection speed V3A along a newlinear trajectory 104A which is different from thetrajectory 101A. - The
satellite droplet 63A does not pass through the intersection point XA because thesatellite droplet 63A flies along thetrajectory 103A different from thetrajectory 101A. Accordingly, thesatellite droplet 63A keeps flying at the speed V4 without colliding with themain droplet 62A ejected from the nozzle 8 bA. Subsequently, as shown inFIG. 1C , theunited droplet 64 lands on theink catching section 30, and thesatellite droplet 63A lands on thepaper 41. Then, as shown inFIG. 1D , theunited droplet 64A, which has landed on theink catching section 30, blends with ink held in theink catching section 30, is sucked up by thecapillary ink passage 10 b, and is delivered to themanifold passage 115 from thecapillary ink passage 10 b. Thesatellite droplet 63, which has landed on thepaper 41, becomes a dot on thepaper 41. - According to the second embodiment as explained above, it is possible to reliably prevent the
satellite droplet 63A from colliding with themain droplet 62A because thesatellite droplet 63A will not pass through the intersection point XA due to the presence of the notchedportion 81. Accordingly, it is possible to eject thesatellite droplet 63A having a small volume of 0.002 to 0.5 pl to be reliably landed on thepaper 41. - While the first and second embodiments have been explained and described as above, the present invention is not limited to the foregoing embodiments and many alternatives, modifications and variations in the constitution or design are possible. For example, in the first embodiment, while the
trajectory 101 of themain droplet 61 ejected from thenozzle 8 a and thetrajectory 103 of thesatellite droplet 63 ejected from 8 a are perpendicular to thepaper 41, thesetrajectories paper 41. - Further, while the first embodiment has the constitution using the
actuator 21 of unimorph type, the actuator may have constitution of, for example, a stacked type piezoelectric actuator and an electrostatic actuator. In addition, the invention may be applied to an ink-jet head based on the thermal system. - In the first embodiment, the ink-jet head is constituted as a line head. However, the ink-jet head may be a serial head. In this case, the ink-jet head may be controlled so that the ink-jet head reciprocates in a direction perpendicular to a direction in which the
paper 41 is transported. With this, it is possible to perform printing on a paper of a larger size with a shorter head. - In addition, in the first and second embodiments, it is arranged so that the
united droplets ink catching section 30. However, theink catching section 30 may be omitted and the united droplet is allowed to land on thepaper 41. In this case, the landed united droplet may be used not as information to be recorded (for example, used for background printing or printing on paper margin). - Further, in the first and second embodiments, while an ink is used as the ejection medium, a conductive paste may be used as the ejection medium. Accordingly, it is possible to print a very fine electric circuit pattern. Also, an organic illuminant may be used as the ejection medium, thereby making it possible to make a high-resolution display devices such as an organic electroluminescence display (OELD). Alternatively, it is possible to use an optical resin as the ejection medium to manufacture a micro array lens or a light guide. Other than these, in applications wherein small dots are formed on a print medium, an ejection medium of other type may be used.
- Furthermore, in the first and second embodiments, the ejection speed of the satellite droplet is lower than the ejection speed of the main droplet. However, in the recent years, a phenomenon that the ejection speed of the satellite droplet becomes faster than the ejection speed of the main droplet. Such a phenomenon may also be applied to the present invention.
- Moreover, in the first and second embodiments, the
satellite droplets nozzles 8 a, 8 aA, respectively, while no satellite droplet is ejected from thenozzles 8 b, 8 bA. However, the present invention is not limited to these constitutions, and the satellite droplet may be ejected also from thenozzle 8 b (8 bA). In this case, it is preferable that the catchingsection 30 is constituted so that the satellite droplet ejected from thenozzle 8 b (8 bA) can be caught in the catching section, or a dedicated catchingsection 30 for catching the satellite droplet ejected from thenozzle 8 b (8 bA) is separately provided. Also, control may be performed so that the satellite droplet is ejected prior to the ejection of the main droplet.
Claims (21)
L 1/V 1=L 2/V 2, wherein
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2004-068175 | 2004-03-10 | ||
JP2004068175A JP2005254579A (en) | 2004-03-10 | 2004-03-10 | Droplet jet apparatus |
Publications (2)
Publication Number | Publication Date |
---|---|
US20050200647A1 true US20050200647A1 (en) | 2005-09-15 |
US7954916B2 US7954916B2 (en) | 2011-06-07 |
Family
ID=34824591
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/075,055 Expired - Fee Related US7954916B2 (en) | 2004-03-10 | 2005-03-09 | Droplet ejecting apparatus for forming dots on a medium |
Country Status (4)
Country | Link |
---|---|
US (1) | US7954916B2 (en) |
EP (1) | EP1574343B1 (en) |
JP (1) | JP2005254579A (en) |
DE (1) | DE602005010316D1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20070070101A1 (en) * | 2005-09-28 | 2007-03-29 | Hiroto Sugahara | Liquid droplet jetting apparatus |
US20160355016A1 (en) * | 2013-11-22 | 2016-12-08 | Kabushiki Kaisha Toshiba | Inkjet head |
CN107257738A (en) * | 2015-02-26 | 2017-10-17 | 彼得·约伊特 | Drop on demand ink print head and drop on demand ink printing process |
CN107405928A (en) * | 2015-02-26 | 2017-11-28 | 彼得·约伊特 | Drop on demand ink print head and drop on demand ink printing process |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2058130A1 (en) * | 2007-11-09 | 2009-05-13 | Nederlandse Organisatie voor toegepast- natuurwetenschappelijk onderzoek TNO | Droplet selection mechanism |
EP2058129A1 (en) | 2007-11-09 | 2009-05-13 | Nederlandse Organisatie voor toegepast- natuurwetenschappelijk onderzoek TNO | Droplet break-up device |
EP2058131A1 (en) | 2007-11-09 | 2009-05-13 | Nederlandse Organisatie voor toegepast- natuurwetenschappelijk onderzoek TNO | Droplet selection mechanism |
JP5092802B2 (en) * | 2008-03-04 | 2012-12-05 | セイコーエプソン株式会社 | Liquid ejecting head and liquid ejecting apparatus |
PL226753B1 (en) * | 2015-03-17 | 2017-09-29 | Piotr Jeuté | Printing head |
JP6575239B2 (en) * | 2015-09-02 | 2019-09-18 | セイコーエプソン株式会社 | Method for manufacturing functional element |
AU2017306809A1 (en) * | 2016-08-04 | 2019-02-14 | Piotr Jeuté | A drop on demand printing head and printing method |
GB2554445B (en) * | 2016-09-28 | 2019-05-22 | Piotr Jeute | A drop on demand printing head and printing method |
Citations (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4468679A (en) * | 1981-05-11 | 1984-08-28 | Nippon Electric Co., Ltd. | On-demand type ink-jet printer |
US6164748A (en) * | 1997-07-31 | 2000-12-26 | Canon Kabushiki Kaisha | Liquid discharge method and liquid jet apparatus |
US6276774B1 (en) * | 1998-01-24 | 2001-08-21 | Eastman Kodak Company | Imaging apparatus capable of inhibiting inadvertent ejection of a satellite ink droplet therefrom and method of assembling same |
US20020018082A1 (en) * | 2000-07-24 | 2002-02-14 | Seiko Epson Corporation | Ink jet recording apparatus and method for driving ink jet recording head incorporated in the apparatus |
US20020024567A1 (en) * | 2000-08-22 | 2002-02-28 | Brother Kogyo Kabushiki Kaisha | Piezoelectric ink-jet printer head and method of fabricating same |
US20020085068A1 (en) * | 2000-12-28 | 2002-07-04 | Eastman Kodak Company | Drop-masking continuous inkjet printing method and apparatus |
US20020140774A1 (en) * | 2001-03-30 | 2002-10-03 | Olympus Optical Co., Ltd. | Ink head |
US6491737B2 (en) * | 2000-05-22 | 2002-12-10 | The Regents Of The University Of California | High-speed fabrication of highly uniform ultra-small metallic microspheres |
US6520502B1 (en) * | 1999-11-23 | 2003-02-18 | Timothy W. Drouhard | Board game suitable for private or casino play |
US20040046825A1 (en) * | 2002-09-10 | 2004-03-11 | Brother Kogyo Kabushiki Kaisha | Apparatus for ejecting very small droplets |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH02137933A (en) * | 1988-11-18 | 1990-05-28 | Ricoh Co Ltd | Liquid jet recorder |
JP3183745B2 (en) * | 1993-03-31 | 2001-07-09 | キヤノン株式会社 | Ink jet recording apparatus and ink jet recording method |
JP3500692B2 (en) | 1994-04-19 | 2004-02-23 | セイコーエプソン株式会社 | Ink jet recording device |
US6167748B1 (en) | 1998-08-31 | 2001-01-02 | Lockheed Martin Energy Research Corporation | Capacitively readout multi-element sensor array with common-mode cancellation |
JP2001239681A (en) | 2000-02-29 | 2001-09-04 | Sharp Corp | Method and device for discharging luquid for forming image and ink-jet image-forming apparatus with the liquid-discharging device |
JP3631937B2 (en) * | 2000-04-12 | 2005-03-23 | 紀州技研工業株式会社 | Inkjet printer |
US6860588B1 (en) * | 2000-10-11 | 2005-03-01 | Hewlett-Packard Development Company, L.P. | Inkjet nozzle structure to reduce drop placement error |
JP2002154199A (en) | 2000-11-20 | 2002-05-28 | Konica Corp | Ink-jet image forming method and ink-jet image recording apparatus |
JP2002307686A (en) * | 2001-04-10 | 2002-10-23 | Olympus Optical Co Ltd | Ink head |
JP4192732B2 (en) | 2002-09-10 | 2008-12-10 | ブラザー工業株式会社 | Ultra-fine droplet ejection device |
-
2004
- 2004-03-10 JP JP2004068175A patent/JP2005254579A/en active Pending
-
2005
- 2005-03-09 EP EP05005161A patent/EP1574343B1/en not_active Expired - Fee Related
- 2005-03-09 US US11/075,055 patent/US7954916B2/en not_active Expired - Fee Related
- 2005-03-09 DE DE602005010316T patent/DE602005010316D1/en active Active
Patent Citations (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4468679A (en) * | 1981-05-11 | 1984-08-28 | Nippon Electric Co., Ltd. | On-demand type ink-jet printer |
US6164748A (en) * | 1997-07-31 | 2000-12-26 | Canon Kabushiki Kaisha | Liquid discharge method and liquid jet apparatus |
US6276774B1 (en) * | 1998-01-24 | 2001-08-21 | Eastman Kodak Company | Imaging apparatus capable of inhibiting inadvertent ejection of a satellite ink droplet therefrom and method of assembling same |
US6520502B1 (en) * | 1999-11-23 | 2003-02-18 | Timothy W. Drouhard | Board game suitable for private or casino play |
US6491737B2 (en) * | 2000-05-22 | 2002-12-10 | The Regents Of The University Of California | High-speed fabrication of highly uniform ultra-small metallic microspheres |
US20020018082A1 (en) * | 2000-07-24 | 2002-02-14 | Seiko Epson Corporation | Ink jet recording apparatus and method for driving ink jet recording head incorporated in the apparatus |
US20020024567A1 (en) * | 2000-08-22 | 2002-02-28 | Brother Kogyo Kabushiki Kaisha | Piezoelectric ink-jet printer head and method of fabricating same |
US20020085068A1 (en) * | 2000-12-28 | 2002-07-04 | Eastman Kodak Company | Drop-masking continuous inkjet printing method and apparatus |
US6478414B2 (en) * | 2000-12-28 | 2002-11-12 | Eastman Kodak Company | Drop-masking continuous inkjet printing method and apparatus |
US20020140774A1 (en) * | 2001-03-30 | 2002-10-03 | Olympus Optical Co., Ltd. | Ink head |
US20040046825A1 (en) * | 2002-09-10 | 2004-03-11 | Brother Kogyo Kabushiki Kaisha | Apparatus for ejecting very small droplets |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20070070101A1 (en) * | 2005-09-28 | 2007-03-29 | Hiroto Sugahara | Liquid droplet jetting apparatus |
US7686415B2 (en) | 2005-09-28 | 2010-03-30 | Brother Kogyo Kabushiki Kaisha | Liquid droplet jetting apparatus |
US20160355016A1 (en) * | 2013-11-22 | 2016-12-08 | Kabushiki Kaisha Toshiba | Inkjet head |
US9969166B2 (en) * | 2013-11-22 | 2018-05-15 | Kabushiki Kaisha Toshiba | Inkjet head with a plurality of integrated nozzles |
CN107257738A (en) * | 2015-02-26 | 2017-10-17 | 彼得·约伊特 | Drop on demand ink print head and drop on demand ink printing process |
CN107405928A (en) * | 2015-02-26 | 2017-11-28 | 彼得·约伊特 | Drop on demand ink print head and drop on demand ink printing process |
Also Published As
Publication number | Publication date |
---|---|
EP1574343A3 (en) | 2006-09-06 |
EP1574343A2 (en) | 2005-09-14 |
EP1574343B1 (en) | 2008-10-15 |
DE602005010316D1 (en) | 2008-11-27 |
JP2005254579A (en) | 2005-09-22 |
US7954916B2 (en) | 2011-06-07 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7954916B2 (en) | Droplet ejecting apparatus for forming dots on a medium | |
JP4599871B2 (en) | Droplet ejector | |
US8052253B2 (en) | Inkjet head having piezoelectric actuator for restrictor, and image forming method and apparatus having the same | |
JP5065083B2 (en) | Ultra-fine droplet ejection device | |
JP5151473B2 (en) | Inkjet recording device | |
JP3329801B2 (en) | Ink jet recording head | |
US7823997B2 (en) | Droplet ejection device | |
JP2005053072A (en) | Liquid conveying device | |
JP4872894B2 (en) | Droplet ejector | |
US7922305B2 (en) | Liquid ejector | |
JP4192732B2 (en) | Ultra-fine droplet ejection device | |
JP4556561B2 (en) | Droplet ejector | |
JP2004122775A5 (en) | ||
CN100519188C (en) | Inkjet printer | |
JP4828889B2 (en) | Ink jet head driving method, ink jet head, and ink jet recording apparatus | |
JP2012111087A (en) | Liquid jet head and liquid jet apparatus | |
JP2003276196A (en) | Ink jet recording head, and ink jet printer mounted with it | |
JP2012250492A (en) | Liquid jet head unit and liquid jet device | |
JP3826588B2 (en) | Inkjet head device | |
JP5104745B2 (en) | Inkjet head | |
JP5167839B2 (en) | Droplet ejector | |
JP4111726B2 (en) | Droplet ejection head, inkjet recording apparatus, image forming apparatus, and apparatus for ejecting droplets | |
JP2002001945A (en) | Ink jet head and ink jet printing device | |
JP2005288697A (en) | Liquid discharging apparatus | |
JP2003089203A (en) | Liquid drop discharge head and ink jet recorder |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: BROTHER KOGYO KABUSHIKI KAISHA, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SUGAHARA, HIROTO;REEL/FRAME:016374/0204 Effective date: 20050304 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 8TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1552); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 8 |
|
FEPP | Fee payment procedure |
Free format text: MAINTENANCE FEE REMINDER MAILED (ORIGINAL EVENT CODE: REM.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
LAPS | Lapse for failure to pay maintenance fees |
Free format text: PATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES (ORIGINAL EVENT CODE: EXP.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
|
FP | Lapsed due to failure to pay maintenance fee |
Effective date: 20230607 |